1. Field of the Invention
This invention relates to an aperture interlocking device for the picture-taking lens and the viewfinder of a single lens reflex camera of the type which permits interchange of the viewfinder.
2. Description of the Prior Art
In a single lens reflex camera of the type which permits interchange of the viewfinder, an interlocking member engageable and interlocked with a pawl or a projection of the aperture ring of the picture-taking lens (hereinafter referred to as the engaging portion of the aperture ring) is provided in the viewfinder so that the lens aperture information may be transmitted to the exposure control device in the viewfinder by the displacement of the interlocking member corresponding to the movement of the aperture ring.
A pantograph mechanism has been used as an example of such interlocking member. When such pantograph mechanism is used, the axis of rotation of the portion of the mechanism engaged with the engaging portion of the aperture ring is not coincident with the axis of rotation of said engaging portion and this varies the position of contact of the engaging portion on the pantograph mechanism. For this reason, the engaging portion of the pantograph mechanism has unavoidably been formed as a round pin.
Such a round pin has increased the radial space thereof and accordingly led to increased design limitations.
.Iadd.Such an interlocking member is provided in the viewfinder and biased in one direction. When the viewfinder is mounted to the camera notwithstanding that the aperture ring of the picture-taking lens has been set to a value other than the full open or maximum aperture, the interlocking member becomes located at the uninterlockable side of the engaging portion of the aperture ring, whereby it becomes impossible to dismount the lens from the camera or to transmit the lens aperture information. .Iaddend.